Method for preventing offset in printing



Aug. 13, 1935; R. MELTON ET AL 2,011,131

METHOD FORPREVENTING OFFSET IN PRINTING Filed Dec. 14, 1932 INVENTORS ROMlE L. MELTON RAYMOND QBENNER BY HENRY F: K\ROHNER ATTORNEY Patented A g. 13, 1935 UNITED STATES.

PATENT oFF1cE;

METHOD FOR PREVENTING OFFSET IN PRINTING Romie L. Melton, Raymond C. Bonner, and Henry P. Kirchner, Niagara Falls, N. Y., assigncrs to The Carborundum Company,

Niagara Falls,

N. Y., a corporation of Pennsylvania Application December 14, 1932, Serial No. 647,243

1 Claim. (Cl. 101-420) until the ink is thoroughly dry and then print on the opposite side of the sheet. This method of printing is not suited to a modern print shop on account of the excessive expenditure of time that it involves. Various means have been devised to dry the ink on the freshly printed side quickly, as for example, etched aluminum surfaces have been used. These etched surf-aces are moistened for the purpose of forming an ink repelling surface. Printers ink is oily in its nature and therefore does not mix readily with water. Moreover, the condition of the moistened aluminum surface is likely to vary with time because of the tendency to evaporation which depends again on the temperature and humidity of the air. In the method of printing which has just. been described the freshly printed paper passes between a printing roll (for the unprinted side of the paper).

and a supporting roll covered with etched metal the surface of which has been moistened- In still another method of printing, granularly coated paper is used to cover the supporting roll during the second printing process. In this case the side of the paper, which was first printed,, passes into contact with the granular coated' paper as the sheet passes between the second printing roll and the adjacent supporting roll. It is claimed that the granular coated paper contacts forcibly with the freshly printed side over a comparative small area 'since the granular particles resist the pressure exerted by opposite printing roll. The granular particles tend to prevent slipping of the freshly printed side and hence tend to reduce smearing or blurring of the first printed side.

In ordinary granularly coated paper however, the grain is distributed in a haphazard manner so that the fiat-sides of the abrasive grain are found on the rough surface in a large proportion of the granules instead of the sharper points.

The present invention is concerned with the use of elongated grain attached endwise to a backing, and at an angle of 45 to 90 inclusive, with the backing in order that the supporting roll may be covered with a sheet having-a serrated coating in which the distribution of points is comparatively regular. The orientation of the granules also permits more ink to gather on the sides of the granules without smearing than would be the case with a supporting surface in which a large proportion of the granules have fiat sides 5 on the outer surface of the sheet.

The desired orientation of the granular particles may be secured by means of theapparatus described and claimed in our co-pending application Serial No. 647,241, filed December 14, 1932. 10 As disclosed in this application an oriented granular coating is produced by projecting such granular particles upwardly from a movable carrier onto the underside of a downwardly facing adhesive coated web. 35

Further specific forms of devices for orienting the particles on granular coated webs are disclosed in our co-pending application, Serial No.

' 636,982, filed October 10, 1932, in which granular particles are. electrostatically oriented and ap-. plied to a downwardly facing adhesive coated web. Another form of device which may be employed is that described in our co-pending application, Serial No. 637,016, filed October 10, 1932,

in which magnetically susceptible particles are 25 applied to an adhesive coated surface, a desired orientation of the particles being secured by the action of a magnetic field. K r

The use of oriented-grain to prevent ofiset m I printing is illustrated by means of the accomg panying drawing in which:

Figure 1 is a sectional elevation of a printing apparatus illustrating a method of printingon both sides in which one of the supporting rolls is shown as covered with oriented grain; 35 Figure 2 is a fragmentary enlarged sectional view showing the action of the type on the web and showing supporting granules (on the counter roll) which lie adjacentto the portion of the sheet being printed; 40-

Figure 3 is an enlarged section through a sheet having a random coating of granules; and

Figure 4 is a similar enlarged section through a sheethaving a coating of oriented granules.

In the. process of printing on both sides of 45 paper or other suitable material, a sheet 2 (see Fig. l) is passed between a printing roll 3 and a counter roll 4, the printing roll being inked by means of an ink roll 5. The sheet then passes along with fresh'printing on its lower side until 50 it comes in contact with the granular coated surface of the supporting roll 6. The oppositely disposed printing roll I now prints the reverse side (upper side in Fig. 1) of the sheet 2. During this printing process the side of the sheet which I which becomes detached from the freshly printed 9. The oriented grain the sides of the granules surface can therefore be before smearsurface and runs down used for a comparatively long time ing occurs.

Figure 4 is an enlarged view and shows more clearly the general character of the granular coated web for covering the surface of the counter roll 6.- The elongated granules 9. are uniformly spaced and so pos'tioned that their longer dimensions are approximately normal to the web backing 8. Granular coated webs which have the granular particles inclined at angles as small as have however been found to be effective in preventing offset in printing. Such oriented coatings support the freshly printed surface at a large number of points and with a minimum of the surface of the individual granules in contact with the inked surface. Such is not the case with the usualgranular coated web illustrated in Figure 3. The granules 10 are haphazardly positioned on the web I l and with their longest dimensions approximately parallel to the surface of the backing. Consequently a larger surface of each granule makes contact with the freshly inked surface and greatly increases the tendency to smear or blur.

Some of the advantages a granular coating of the type above for preventing or reducing oifset in printing may which are claimed for be summarized as follows:

or quality of the limitation 1. The production of a supe printing is facilitated by reason of i of the contact surface between the freshly printed front surface and the counter roll.

2. The greater ink capacity furnished by a coating of the type desc bed increases the resistance to offsetting. The granularly coated web can thus be used a longer time before it becomes described saturated, that is before it becomes in a condi;

tion to produce serious offsetting or smearing.

3. The useful life of the coated web is increased because 'of the arrangement of thegrain. This is a particularly valu able feature because of the 4. A greater weight of sizing are positioned endwise. This when the granules coating is possible increases the strength of adhesion of the granules to the fabric without sacrificing ink capacity as compared with the usual unoriented granular .coated web, which is typified by Figure 3.

' 5. Coated webs made as described above have a granular coating which is one grain thick. The

coating is thus attached directly to the backing and is more satisfactory than the ordinary coating which may consist of a jumble of granules piled on top of each other.

6. An oriented granular coating provides a greater number of area.

supporting points per unit Various kinds of granules other than those referred' to above may be used, such as granules of crushed quartz, mullite, glass, sillimanite, etc.

It is desirable however,

elongated character not the minimum in general parallel to maximum or larger dimensions of the that the granules be of an so that in the resultant prodgranules are the supporting fabric. The dimensions of the granudes are therefore in general perpendicular to the plane of the fabric. sizing coating is The material of which the formed may likewise be varied within wide limits so long as it can be sprayed around the granules and is capable of being thereafter hardened to reinforce the granular coating;

We claim:

sheet, then bringing relationship with means the said sheet against the said side, and pressing printing means by the said sheet into printing to print on the opposite the points of a layer of upstanding elongated particles which-are separated from each other by a major axes.

distance less than their ROMIE L. MELTON. RAYMOND c. BENNER. HENRY P. KERCHNER. 

